Changing an induction motor voltage

AC, DC, amps, volts and kilowatt. It's all discussed in here
User avatar
Electrocycle
Senior Member
Posts: 985
Joined: Sun, 19 Oct 2008, 20:23
Real Name: Andrew
Location: Sydney
MSN: dumhed@dumhed.com
Contact:

Changing an induction motor voltage

Post by Electrocycle » Fri, 05 Feb 2010, 14:03

Nevilleh wrote:McGuire Electric Car.


still wrong thread, but oh no...
He's measured the cogging torque as the motor output, and the current required to make it turn with no load as the power input.

Doesn't seem to realise that you'd also need to overcome any output load!
The Engine Whisperer - fixer of things

User avatar
weber
Site Admin
Posts: 2229
Joined: Fri, 23 Jan 2009, 17:27
Real Name: Dave Keenan
Location: Brisbane
Contact:

Changing an induction motor voltage

Post by weber » Thu, 11 Feb 2010, 15:29

antiscab wrote: free energy?
was that post meant for this thread?
i think you've lost me Nevilleh   *confused*
Matt

Hi Matt,

Neville is referring back to the Loo Tech Electricity Amplifier whose invention was indeed first announced in this very thread back in July 2009.

[Edit: Fixed broken link]
Last edited by weber on Sun, 27 Oct 2013, 05:27, edited 1 time in total.
One of the fathers of MeXy the electric MX-5, along with Coulomb and Newton (Jeff Owen).

antiscab
Senior Member
Posts: 2108
Joined: Mon, 26 Nov 2007, 05:39
Real Name: Matthew Lacey
Location: Perth, WA

Changing an induction motor voltage

Post by antiscab » Fri, 12 Feb 2010, 00:57

ah, righto....a blast from the past post then :)

confusion over :)

Matt
Matt
2008 Mazda 2 - EV Shop convert
2011 Blade Electron mk6
2007 vectrix - 117'000km
1993 Electrolux - needs batt and charger
1998 Prius - needs batt
1999 Prius - needs batt

User avatar
a4x4kiwi
Senior Member
Posts: 772
Joined: Thu, 03 Jan 2008, 19:04
Real Name: Malcolm Faed
Location: Australia
Contact:

Changing an induction motor voltage

Post by a4x4kiwi » Sat, 20 Feb 2010, 16:58

I just pulled my motor out with a view to placing the phases in parallel in order to convert it to 220v star. Unfortunately the wiring is all gooped up with a hard brittle substance preventing getting into it.

I am also fitting an 800ppr encoder. See my blog for details and full resolution photos.

Here are some photos.

Image

Image

Image
Silicon is just sand with attitude.

Blog: http://malfunction.faed.name

HeadsUp
Groupie
Posts: 235
Joined: Sat, 28 Feb 2009, 09:13
Real Name: Mark Whatley
Location: Sydney
MSN: alexandria63@hotmail.com

Changing an induction motor voltage

Post by HeadsUp » Sat, 20 Feb 2010, 17:02

are you going to try and soften it with any solvent to loosen it up ?

what would do that without damaging the insulation on the wires ?

Buddha...There are only two mistakes one can make along the path to truth - not going all the way and not starting

User avatar
woody
Senior Member
Posts: 1694
Joined: Sat, 21 Jun 2008, 02:03
Real Name: Anthony Wood
Location: Mt Colah

Changing an induction motor voltage

Post by woody » Sat, 20 Feb 2010, 18:39

Just having a look at the piccies and in reference to Chapter 4 of the "Electric Motor Repair":

Looks like a "Consequent Pole" 4 pole motor with concentric windings

(starting at the top going clockwise)

Phase A is
A1: 1-12 2-11 3-10
A2: 19-30 20-29 21-28

Phase B is
B1: 13-24 14-23 15-22
B2: 31-6 32-5 33-4

Phase C is
C1: 25-36 26-35 27-34
C2: 7-18 8-17 9-16

I can see fat wires coming out of the outer of slots 6, 24, 30, and the inner of slot 33.

There will be 6 wires coming from the terminal box.

It looks like A1 & A2 etc. are in parallel already, looking at the connections on top around slot 27-36.

If you're feeling keen you can pull apart these insulated wires and maybe convert to 2 pole 30kW by reversing A2,B2,C2 connections.

Probably the best thing to do is take lots of photos, work out which wires go where as best you can, and put it all back together without breaking anything.

Then you can do some homework, figure out if anything good is possible, and pull it out again later and do it.

cheers,
Woody
Planned EV: '63 Cortina using AC and LiFePO4 Battery Pack

User avatar
coulomb
Site Admin
Posts: 3025
Joined: Thu, 22 Jan 2009, 20:32
Real Name: Mike Van Emmerik
Location: Brisbane
Contact:

Changing an induction motor voltage

Post by coulomb » Sat, 20 Feb 2010, 20:25

woody wrote: It looks like A1 & A2 etc. are in parallel already, looking at the connections on top around slot 27-36.
Yes, sadly, this seems to be the common configuration.

So the only recourse is to find the centre tap of each slot pair (all 18 of them), and wire each half in parallel with the other:

Image

That would give you a 207.5 V delta (or 360 V star) 4-pole motor. It sure seems like a lot of work. Then, there is the problem of finding the centre of the winding to cut it; I can't think of a reasonable way.

Maybe you can put pulses at one end, and measure the ~2.6 nanoseconds of delay that each extra ~800 mm of wire in each turn would give you. Perhaps you can capacitively or inductively couple to the wire without cutting it. Perhaps there are instruments you could hire, designed to find faults in cables perhaps, that do this for you somehow. You could perhaps simulate a fault by clamping some sort of magnetic short circuit around the wire. Start with the clamp at the end of the winding, note the distance, and find the wire with exactly half that distance.

It's so frustrating; all the wire is already there, it just needs to be reconfigured a little. Yet the only way seems to be to burn out all the old wire and start again!
Learning how to patch and repair PIP-4048 inverter-chargers and Elcon chargers.

User avatar
weber
Site Admin
Posts: 2229
Joined: Fri, 23 Jan 2009, 17:27
Real Name: Dave Keenan
Location: Brisbane
Contact:

Changing an induction motor voltage

Post by weber » Sat, 20 Feb 2010, 20:31

a4x4kiwi wrote: I am also fitting an 800ppr encoder. See my blog for details and full resolution photos.

Hi Mal, coulomb and I are in the market for an encoder now too.

In another thread acmotor suggested one for about $200 from RS Components, but the only one I could find that matched that description has a 4 mm diameter solid shaft, which means it needs a flexible coupling and precise alignment. It seems designed for much smaller motors as I couldn't find a flexible coupling that could tolerate the typical end-float of a 132-frame induction motor. And Ross Pink warned me against using solid shaft encoders anyway and swears by hollow shaft encoders because flexible couplings don't last and mounting is allowed to be much less precise with a hollow shaft.

So can you tell us a price for that INGH 12HS 33AM 00800 encoder? Why did you go for 800 ppr? Ross Pink suggests the version with differential outputs for noise immunity. And we'd only need a 2 m cable so that would be an INGH 12HS 27AM 00800. I guess it depends what they keep in stock?
One of the fathers of MeXy the electric MX-5, along with Coulomb and Newton (Jeff Owen).

User avatar
coulomb
Site Admin
Posts: 3025
Joined: Thu, 22 Jan 2009, 20:32
Real Name: Mike Van Emmerik
Location: Brisbane
Contact:

Changing an induction motor voltage

Post by coulomb » Sat, 20 Feb 2010, 20:47

woody wrote: If you're feeling keen you can pull apart these insulated wires and maybe convert to 2 pole 30kW by reversing A2,B2,C2 connections.

For a conversion that is keeping the gearbox (so you are wanting something like 3000 RPM in the middle of the motor's speed range), that seems like a reasonable compromise: get a cheap 4-pole motor that has consequent poles, and do the easy rewire for 2 poles and double the power. Use the gearbox to turn the extra speed into more torque for low speed.

I can't help feeling that this rewire is "getting something for nothing". Will you really get the same torque at twice the speed by just swapping the windings? It seems to me that you would somehow get half the torque when the speed doubles.

Can someone help me imagine this correctly?   Image
Learning how to patch and repair PIP-4048 inverter-chargers and Elcon chargers.

User avatar
woody
Senior Member
Posts: 1694
Joined: Sat, 21 Jun 2008, 02:03
Real Name: Anthony Wood
Location: Mt Colah

Changing an induction motor voltage

Post by woody » Sat, 20 Feb 2010, 21:35

coulomb wrote:
woody wrote: If you're feeling keen you can pull apart these insulated wires and maybe convert to 2 pole 30kW by reversing A2,B2,C2 connections.

Can someone help me imagine this correctly?   Image
The 2 pole would probably be less efficient that a dedicated two pole, more like a dahlander 2 speed.

That aside:

Each of A1 and A2 with the same current would now be making a field in the same direction (e.g. left to right) instead of against each other (e.g. outer to inner) + a consequent/phantom pole (inner to outer).

So that means only half the flux lines for the rotor to cut, i.e a quarter of the torque.

We can't increase the current as we're all out of voltage.

I'm not helping, am I. Image

going back to dahlander:
Motor Book wrote: Constant torque Dahlander is For constant torque, the motor is usually connected two-parallel star for high speed and series-delta for low speed.

For constant horsepower the connection is two-parallel star for low speed and series delta for high speed.
Both of dahlander windings require series delta.

Back to crazy ideas:

Rewind for 2/3 voltage:

Cut the jumpers between the concentric windings and re-pair them as

Outer + Inner, Inner + outer, Middle + Middle for approximately the same resistance.

I.E. A is currently made up of ('=' means coils '-' means series connection)

1=12-2=11-3=10 in parallel with 19=30-20=29-21=28

Reconnecting the coils as:
1=12-21=28 and 2=11-20=29 and 3=10-19=30 in parallel

This gives Mal 480V star (720V * 2/3) and 275V delta.

Worth a bash when you have the money for a rewind when it all goes pear-shaped.

275V should give 230Nm @ 2200rpm (56kph) i.e. 53kW
0-90 in 17 seconds instead of 31.
top speed 120 instead of 95

cheers,
Woody
Planned EV: '63 Cortina using AC and LiFePO4 Battery Pack

User avatar
coulomb
Site Admin
Posts: 3025
Joined: Thu, 22 Jan 2009, 20:32
Real Name: Mike Van Emmerik
Location: Brisbane
Contact:

Changing an induction motor voltage

Post by coulomb » Sat, 20 Feb 2010, 22:09

woody wrote: I'm not helping, am I. Image
For this part, err, no.
Rewind for 2/3 voltage:

Cut the jumpers between the concentric windings and re-pair them as

Outer + Inner, Inner + outer, Middle + Middle for approximately the same resistance.

... Reconnecting the coils as:
1=12-21=28 and 2=11-20=29 and 3=10-19=30 in parallel
That's brilliant! You end up with a coil spanning 11 teeth in series with a coil spanning 7 teeth, for a total of 18 teeth, in parallel with a 9+9 and a 7+11, so they all span 18 teeth!

However, I wonder if the middle slot pairs (like 2=11 in series with 20=20) might get more voltage induced because they are less affected by adjacent slots that are out-of-phase. I also wonder if there is a good way of measuring the circulating currents, after you try something like this.

Of course, this still has the problem of finding the 12 wires that cross from one slot pair to another (e.g. where 1=12 currently connects to 2=11).
Learning how to patch and repair PIP-4048 inverter-chargers and Elcon chargers.

User avatar
a4x4kiwi
Senior Member
Posts: 772
Joined: Thu, 03 Jan 2008, 19:04
Real Name: Malcolm Faed
Location: Australia
Contact:

Changing an induction motor voltage

Post by a4x4kiwi » Sun, 21 Feb 2010, 13:57

Hi all,

I selected the encoder based on the Danfoss input max frequency with a push pull driver is 65khz. This equates to 886 pulses per revolution at 4400rpm.

Encoders are usually available in 100 increment steps. They did not have it x stock but it arrived from Germany within 2 weeks. Give them a call. Jill was very helpful.

The price was $491 +GST. The price had just came down by $50 due to exchange rate changes.
Silicon is just sand with attitude.

Blog: http://malfunction.faed.name

User avatar
a4x4kiwi
Senior Member
Posts: 772
Joined: Thu, 03 Jan 2008, 19:04
Real Name: Malcolm Faed
Location: Australia
Contact:

Changing an induction motor voltage

Post by a4x4kiwi » Sun, 21 Feb 2010, 14:03

Silicon is just sand with attitude.

Blog: http://malfunction.faed.name

User avatar
weber
Site Admin
Posts: 2229
Joined: Fri, 23 Jan 2009, 17:27
Real Name: Dave Keenan
Location: Brisbane
Contact:

Changing an induction motor voltage

Post by weber » Sun, 21 Feb 2010, 16:15

Woody, that 2/3 rewind idea is clever. You've solved the different resistance problem, but unfortunately not the different waveform problem, so there would be circulating harmonic currents as coulomb mentioned. But how bad they would be is another question. But based on coulomb's and my experience of trying to find the crossover wires on a motor with _clear_ varnish, the chances of finding all 12 of them on Mal's motor are slim to nonexistent.

Thanks for a neat notation too, Woody.

Mal, thanks for the info re the encoder, and the photo on the lathe. We need to put a taper-lock hub on our fan shaft to couple to our aircon/power-steering pulley, so Ross Pink suggests adding a shaft extension for the encoder by precisely drilling and tapping into the end of the shaft and threading a 12 mm dia post in.

I'm wondering if that can be done without a lathe and without removing the shaft, by powering the motor and mounting the drill in a vise or something?
One of the fathers of MeXy the electric MX-5, along with Coulomb and Newton (Jeff Owen).

User avatar
Hemonster
Groupie
Posts: 90
Joined: Mon, 01 Dec 2008, 00:28
Location: Christchurch NZ

Changing an induction motor voltage

Post by Hemonster » Sun, 21 Feb 2010, 17:12

Hi Mal,

Interested in your update, thanks for posting.
a4x4kiwi wrote:
I selected the encoder based on the Danfoss input max frequency with a push pull driver is 65khz. This equates to 886 pulses per revolution at 4400rpm.


Is this really enough pulses per revolution? The recommended for the controller I have (a PDL VFD) is 1000-2000 ppr per motor pole pair (sounds like a lot to me). The minimum they say is 500 ppr per pole pair, so for your 4-pole motor would be 1000 ppr minimum.

I think the higher the ppr the better the control at low rpm, is this true?




User avatar
Johny
Senior Member
Posts: 3636
Joined: Mon, 23 Jun 2008, 16:26
Real Name: John Wright
Location: Melbourne
Contact:

Changing an induction motor voltage

Post by Johny » Sun, 21 Feb 2010, 17:19

I'm not sure about these but sometime in the last 2 weeks I got an email from some company (regular advertising stuff) about a contact free shaft encoder. I following it up enough to find that farnell stocked them but lost interest because I figured I already had an 8mm shaft.
They claimed a wide tolerance for mis-mounting and use a magnetic coupler which is glued to the end of a shaft. I'm sorry I can't make it easier but if you think that the motor magnetic field won't interfere it may be worth looking into.

Squiggles
Senior Member
Posts: 742
Joined: Wed, 22 Apr 2009, 03:19
Real Name: Neil
Location: Newcastle NSW

Changing an induction motor voltage

Post by Squiggles » Sun, 21 Feb 2010, 18:02

Hemonster wrote: Hi Mal,

Interested in your update, thanks for posting.
a4x4kiwi wrote:
I selected the encoder based on the Danfoss input max frequency with a push pull driver is 65khz. This equates to 886 pulses per revolution at 4400rpm.


Is this really enough pulses per revolution? The recommended for the controller I have (a PDL VFD) is 1000-2000 ppr per motor pole pair (sounds like a lot to me). The minimum they say is 500 ppr per pole pair, so for your 4-pole motor would be 1000 ppr minimum.

I think the higher the ppr the better the control at low rpm, is this true?

I am amazed that in the days of high speed digital computing that there is a need for anything like 800ppr. even 360 gives an absolute resolution of 1 deg and effectively this can be doubled by software.
With slip variable between 0 & 4% and the maximum rate of change of angular velocity of the rotor relatively low why there is a need for super high resolution baffles me Image

Squiggles
Senior Member
Posts: 742
Joined: Wed, 22 Apr 2009, 03:19
Real Name: Neil
Location: Newcastle NSW

Changing an induction motor voltage

Post by Squiggles » Sun, 21 Feb 2010, 18:03

weber wrote:

Mal, thanks for the info re the encoder, and the photo on the lathe. We need to put a taper-lock hub on our fan shaft to couple to our aircon/power-steering pulley, so Ross Pink suggests adding a shaft extension for the encoder by precisely drilling and tapping into the end of the shaft and threading a 12 mm dia post in.


Be careful that it does not unscrew itself when you reverse the motor.

User avatar
a4x4kiwi
Senior Member
Posts: 772
Joined: Thu, 03 Jan 2008, 19:04
Real Name: Malcolm Faed
Location: Australia
Contact:

Changing an induction motor voltage

Post by a4x4kiwi » Mon, 22 Feb 2010, 01:44

More progress... http://a4x4kiwi.blogspot.com/2010/02/mo ... coder.html

I didn't know about the 500 pulses per pole pair. Here's hoping 800 is enough.
Last edited by a4x4kiwi on Sun, 21 Feb 2010, 14:54, edited 1 time in total.
Silicon is just sand with attitude.

Blog: http://malfunction.faed.name

User avatar
coulomb
Site Admin
Posts: 3025
Joined: Thu, 22 Jan 2009, 20:32
Real Name: Mike Van Emmerik
Location: Brisbane
Contact:

Changing an induction motor voltage

Post by coulomb » Mon, 22 Feb 2010, 06:03

a4x4kiwi wrote: More progress...

Good to see.

Just one comment... with an 800 pulse per revolution encoder (so 0.45 degrees between pulses), maybe the slight movement from that coat hanger wire might be enough to cause jitter in the least significant few bits? Perhaps more so when changing from reverse to forward, and vice versa.

0.45 degrees is about 0.2 mm at 25 mm radius. Would it move that much/little?

I don't have any idea whether it might move that much or not, but it seems possible that a totally rigid connection from resolver/encoder to the motor case may be needed. For simplicity's sake, I hope not!
Learning how to patch and repair PIP-4048 inverter-chargers and Elcon chargers.

User avatar
a4x4kiwi
Senior Member
Posts: 772
Joined: Thu, 03 Jan 2008, 19:04
Real Name: Malcolm Faed
Location: Australia
Contact:

Changing an induction motor voltage

Post by a4x4kiwi » Mon, 22 Feb 2010, 12:33

That crossed my mind too.

In the mounting instructions they suggest a 2.5mm pin screwed into the body of the motor. I think that would also have some movement.
Silicon is just sand with attitude.

Blog: http://malfunction.faed.name

User avatar
Johny
Senior Member
Posts: 3636
Joined: Mon, 23 Jun 2008, 16:26
Real Name: John Wright
Location: Melbourne
Contact:

Changing an induction motor voltage

Post by Johny » Wed, 24 Feb 2010, 15:25

Just in case it's useful I tracked down that contact-free shaft encoder I mentioned a few posts up. Unfortunately it's only a 256 CPR.
It's an AVAGO. Around $25.
http://www.avagotech.com/pages/en/motio ... t-601bf06/
Last edited by Johny on Wed, 24 Feb 2010, 04:25, edited 1 time in total.

User avatar
a4x4kiwi
Senior Member
Posts: 772
Joined: Thu, 03 Jan 2008, 19:04
Real Name: Malcolm Faed
Location: Australia
Contact:

Changing an induction motor voltage

Post by a4x4kiwi » Wed, 24 Feb 2010, 15:55

I updated progress here
Silicon is just sand with attitude.

Blog: http://malfunction.faed.name

Huub35
Groupie
Posts: 42
Joined: Wed, 24 Mar 2010, 13:47

Changing an induction motor voltage

Post by Huub35 » Sun, 25 Apr 2010, 02:53

woody wrote:
coulomb wrote:
woody wrote: If you're feeling keen you can pull apart these insulated wires and maybe convert to 2 pole 30kW by reversing A2,B2,C2 connections.

Can someone help me imagine this correctly?   Image
....


Back to crazy ideas:

Rewind for 2/3 voltage:

Cut the jumpers between the concentric windings and re-pair them as

Outer + Inner, Inner + outer, Middle + Middle for approximately the same resistance.


.....
cheers,
Woody


Dear all,

just bought a 7.5 kW four pole. Windings in 400 V Delta, 690 Star (or thereabout). Originally thought that this might be a good motor to test (it was dirty and cheap)inverter etc., but now also starting to consider to use this as a drive motor for a lighter car.

I know in Germany drives a Opel Corsa with a 5.5 kW 4-pole, and that is working.

However, getting something better for free remains very appealing, so I was thinking about rewiring it into a lower voltage. My inverter does 55 kW continous, and I would keep the clutch + gearbox for a start.

My question is, how to recognize the several windings. Should I post a picture here, or is there some general knowhow that I can immediately use to determine the type of winding?

Pictures is difficult as I do not know how to do that :-0, and also as the motor is in storage a bit farther away.

Many thanks for your thoughts about this, regards,


Huub

User avatar
coulomb
Site Admin
Posts: 3025
Joined: Thu, 22 Jan 2009, 20:32
Real Name: Mike Van Emmerik
Location: Brisbane
Contact:

Changing an induction motor voltage

Post by coulomb » Sun, 25 Apr 2010, 06:35

Huub35 wrote: My question is, how to recognize the several windings. Should I post a picture here, or is there some general knowhow that I can immediately use to determine the type of winding?

One quick indication is if you see wires from the junction box joining with two or more windings wires. That means that some windings are already in parallel, so it's not going to be trivial to arrange them for lower voltage.

Every motor of reasonable size that I've seen seems to have windings already in parallel. So that "for free" gain doesn't seem to arise very often.
Learning how to patch and repair PIP-4048 inverter-chargers and Elcon chargers.

Post Reply